Knives to cut foam core board?

[John Murphy]

Hello.

I have a customer with some foam core board with printing on both sides. They asked if I could cut out the printed signs from the board. I'm sure I can handle the data, but I am not sure rotary cutting is the way to go.

The board is only 3/16 thick, so I don't think I can find a compression cutter able to try.

My question is: Are there any knives that are successful at cutting this material nice and clean? I know this is mainly directed to the sign/printer people, but I don't want to waste allot of time trying things that have already failed. If you have a brand name, or type of cutter to look for, this would be a great start for me.

Thanks

JOhn

[gravirozo]

hello


make a testcut with a straigh bit... on point what is far from the sign... that posted be to work....
the flute need to be straight... not spiral...


thanks
viktor


but i don't have solution for the offset between the two side picture...

[cabnet636]

1/8" spiral downcut bit, test and template file before cutting or run it in the air .25 above material before to check registration

jim

[cabnet636]

viktor may be right about straight bit

[moto633]

I cut some foam core with a 1/4in compresion spiral from Cenurion tools not long ago it has .20 up cut on the tip. The results were ok for what I was doing but I highly suggest test cutting. I paid $13.00 for a 4x8 sheet of .187 foam core. Pretty cheap to do some tests on. Or get a scrap from your customer.

Good luck and let us know how it goes!!

Nick

[keelhauled]

I cut that stuff all the time with a 6mm two flute downcut spiral. The secret is to ramp in ramp out cause if you plunge straight down and the bit is not razor sharp it can leave a dent.

[John Murphy]

Hello.

Thanks so much for the tips. I had the customer drop off a couple of pieces to test last night.

I was thinking about using a straight bit, but I kind of ruled it out. I am going to give it a try this morning.

Thanks for the replies. This is great forum, and an even better group of professionals.
I'll let you know how it works out later today.

John

[knighttoolworks]

i made this knife for cutting cardboard. it works pretty well. but you manually have to turn it for straight cuts.

[Rcnewcomb]

You could contact the folks at WidgetWorksUnlimited.com

Here was a post of theirs from another forum:

WidgetWorks Specialty Bits - Drag Knife Bit
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Let's Talk ShopBot: Product/Supplier List and Requests: WidgetWorks Specialty Bits - Drag Knife Bit
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Posted by Russ Todd on Tuesday, December 02, 2008 - 11:00 am:
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I'll pipe in so you can hear it straight from the horses mouth...
Our drag knife bits are designed to cut sand blast mask as well as regular sign vinyl. In fact, the pressure can be adjusted high enough to cut cardboard and thin plastics.

If you plan to cut anything other than sign vinyl (such as sand blast mask) you'll need to order an additional 60 degree blade. (the bits ship with a 45 degree blade included.

ShopBot may carry our replacement blades in the future. For now, replacement blades (both 45 and 60 degree) can be ordered directly through us.

Please see our website for contact/ordering info:
WidgetWorksUnlimited.com

[John Murphy]

Thanks for the feedback guys.

Todays test went less than great. Allot of fuzzy material and frayed edges. The first piece they gave me had a coating of some sort, that didn't cut well at all.

I tried a 3/32 straight bit(only straight bit that I had that would cut through) and ramped in as suggested. The results where disappointing. Second try was with a down shear 3/8dia. Pretty much the same results. I know my down shear cutter was not as sharp as it should be for this test. I stopped, and will try again when I get a sharper tool. In the mean time, I am going to start looking for a knife system.

Thanks for the lead Randall.

john

[John Murphy]

P.S.

Knighttools.

I like the tool you made. does it follow the direction of the cut when your moving, or are you constantly adjusting?

John

[gravirozo]

hello

it might looks dummy, but if the conturs are not so complex, might be you can cut just by hand?


sometime the handwork faster like programming, positioning ... 3/16 is not so thick... and of descriptions it looks some very soft foam... a razorknife can works well...

also with knife, as i know the roland has some selfaligning plotterknife... but that only for 1/16... because in small radiuses the knife doesn't works well...


thanks
viktor

probably i missed something,,, but i just did not read about... on that website,,,, randall offer.... i saw nothing about the """loops""" the selfaligning blade need to go "over" on the node and with a loop turning, as the knife point keep in one point, and cut sharp corners... again just about roland cutters, they makes it of "hardware"...

[knighttoolworks]

the knife will do curves but not angles. so you need to have the knife facing the right way to start the cut. it can swivel just fine. so for rectangle cuts you need to make single line drawings. they need to overshoot a bit too. I do all y and x cuts separately. I make the start points match so they cut ll the same direction. then I make toolpath for y and one for x. then I only need to set the knife once for each toolpath. not perfect but it saves me a lot of money over motorizing it. a smaller blade would le me make smaller curves. but I mostly cut 1/2" cardboard with it.

[John Murphy]

Thanks for the advice guys.

The contours for the customer are quite complex. They have tried cutting by hand, but are looking for something faster and more accurate. I am looking into options, but for now I am going to have to decline this job.

Thanks again for all the great responses.

John

[gravirozo]

hello

still you can get some money from them... making a plywood pattern-template as they can draw-cut around... you already worked with...

thanks
viktor